arch/arm/kernel/smp_twd.c

   1 /*
   2  *  linux/arch/arm/kernel/smp_twd.c
   3  *
   4  *  Copyright (C) 2002 ARM Ltd.
   5  *  All Rights Reserved
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/clk.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/delay.h>
  16 #include <linux/device.h>
  17 #include <linux/err.h>
  18 #include <linux/smp.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/clockchips.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/io.h>
  23 #include <linux/of_irq.h>
  24 #include <linux/of_address.h>
  25
  26 #include <asm/smp_twd.h>
  27 #include <asm/localtimer.h>
  28 #include <asm/hardware/gic.h>
  29
  30 /* set up by the platform code */
  31 static void __iomem *twd_base;
  32
  33 static struct clk *twd_clk;
  34 static unsigned long twd_timer_rate;
  35
  36 static struct clock_event_device __percpu **twd_evt;
  37 static int twd_ppi;
  38
  39 static void twd_set_mode(enum clock_event_mode mode,
  40                         struct clock_event_device *clk)
  41 {
  42         unsigned long ctrl;
  43
  44         switch (mode) {
  45         case CLOCK_EVT_MODE_PERIODIC:
  46                 /* timer load already set up */
  47                 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
  48                         | TWD_TIMER_CONTROL_PERIODIC;
  49                 __raw_writel(twd_timer_rate / HZ, twd_base + TWD_TIMER_LOAD);
  50                 break;
  51         case CLOCK_EVT_MODE_ONESHOT:
  52                 /* period set, and timer enabled in 'next_event' hook */
  53                 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
  54                 break;
  55         case CLOCK_EVT_MODE_UNUSED:
  56         case CLOCK_EVT_MODE_SHUTDOWN:
  57         default:
  58                 ctrl = 0;
  59         }
  60
  61         __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
  62 }
  63
  64 static int twd_set_next_event(unsigned long evt,
  65                         struct clock_event_device *unused)
  66 {
  67         unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
  68
  69         ctrl |= TWD_TIMER_CONTROL_ENABLE;
  70
  71         __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
  72         __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
  73
  74         return 0;
  75 }
  76
  77 /*
  78  * local_timer_ack: checks for a local timer interrupt.
  79  *
  80  * If a local timer interrupt has occurred, acknowledge and return 1.
  81  * Otherwise, return 0.
  82  */
  83 static int twd_timer_ack(void)
  84 {
  85         if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
  86                 __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
  87                 return 1;
  88         }
  89
  90         return 0;
  91 }
  92
  93 static void twd_timer_stop(struct clock_event_device *clk)
  94 {
  95         twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
  96         disable_percpu_irq(clk->irq);
  97 }
  98
  99 #ifdef CONFIG_CPU_FREQ
 100
 101 /*
 102  * Updates clockevent frequency when the cpu frequency changes.
 103  * Called on the cpu that is changing frequency with interrupts disabled.
 104  */
 105 static void twd_update_frequency(void *data)
 106 {
 107         twd_timer_rate = clk_get_rate(twd_clk);
 108
 109         clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate);
 110 }
 111
 112 static int twd_cpufreq_transition(struct notifier_block *nb,
 113         unsigned long state, void *data)
 114 {
 115         struct cpufreq_freqs *freqs = data;
 116
 117         /*
 118          * The twd clock events must be reprogrammed to account for the new
 119          * frequency.  The timer is local to a cpu, so cross-call to the
 120          * changing cpu.
 121          */
 122         if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE)
 123                 smp_call_function_single(freqs->cpu, twd_update_frequency,
 124                         NULL, 1);
 125
 126         return NOTIFY_OK;
 127 }
 128
 129 static struct notifier_block twd_cpufreq_nb = {
 130         .notifier_call = twd_cpufreq_transition,
 131 };
 132
 133 static int twd_cpufreq_init(void)
 134 {
 135         if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk))
 136                 return cpufreq_register_notifier(&twd_cpufreq_nb,
 137                         CPUFREQ_TRANSITION_NOTIFIER);
 138
 139         return 0;
 140 }
 141 core_initcall(twd_cpufreq_init);
 142
 143 #endif
 144
 145 static void __cpuinit twd_calibrate_rate(void)
 146 {
 147         unsigned long count;
 148         u64 waitjiffies;
 149
 150         /*
 151          * If this is the first time round, we need to work out how fast
 152          * the timer ticks
 153          */
 154         if (twd_timer_rate == 0) {
 155                 printk(KERN_INFO "Calibrating local timer... ");
 156
 157                 /* Wait for a tick to start */
 158                 waitjiffies = get_jiffies_64() + 1;
 159
 160                 while (get_jiffies_64() < waitjiffies)
 161                         udelay(10);
 162
 163                 /* OK, now the tick has started, let's get the timer going */
 164                 waitjiffies += 5;
 165
 166                                  /* enable, no interrupt or reload */
 167                 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
 168
 169                                  /* maximum value */
 170                 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
 171
 172                 while (get_jiffies_64() < waitjiffies)
 173                         udelay(10);
 174
 175                 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
 176
 177                 twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
 178
 179                 printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,
 180                         (twd_timer_rate / 10000) % 100);
 181         }
 182 }
 183
 184 static irqreturn_t twd_handler(int irq, void *dev_id)
 185 {
 186         struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
 187
 188         if (twd_timer_ack()) {
 189                 evt->event_handler(evt);
 190                 return IRQ_HANDLED;
 191         }
 192
 193         return IRQ_NONE;
 194 }
 195
 196 static struct clk *twd_get_clock(void)
 197 {
 198         struct clk *clk;
 199         int err;
 200
 201         clk = clk_get_sys("smp_twd", NULL);
 202         if (IS_ERR(clk)) {
 203                 pr_err("smp_twd: clock not found: %d\n", (int)PTR_ERR(clk));
 204                 return clk;
 205         }
 206
 207         err = clk_prepare(clk);
 208         if (err) {
 209                 pr_err("smp_twd: clock failed to prepare: %d\n", err);
 210                 clk_put(clk);
 211                 return ERR_PTR(err);
 212         }
 213
 214         err = clk_enable(clk);
 215         if (err) {
 216                 pr_err("smp_twd: clock failed to enable: %d\n", err);
 217                 clk_unprepare(clk);
 218                 clk_put(clk);
 219                 return ERR_PTR(err);
 220         }
 221
 222         return clk;
 223 }
 224
 225 /*
 226  * Setup the local clock events for a CPU.
 227  */
 228 static int __cpuinit twd_timer_setup(struct clock_event_device *clk)
 229 {
 230         struct clock_event_device **this_cpu_clk;
 231
 232         if (!twd_clk)
 233                 twd_clk = twd_get_clock();
 234
 235         if (!IS_ERR_OR_NULL(twd_clk))
 236                 twd_timer_rate = clk_get_rate(twd_clk);
 237         else
 238                 twd_calibrate_rate();
 239
 240         __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
 241
 242         clk->name = "local_timer";
 243         clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT |
 244                         CLOCK_EVT_FEAT_C3STOP;
 245         clk->rating = 350;
 246         clk->set_mode = twd_set_mode;
 247         clk->set_next_event = twd_set_next_event;
 248         clk->irq = twd_ppi;
 249
 250         this_cpu_clk = __this_cpu_ptr(twd_evt);
 251         *this_cpu_clk = clk;
 252
 253         clockevents_config_and_register(clk, twd_timer_rate,
 254                                         0xf, 0xffffffff);
 255         enable_percpu_irq(clk->irq, 0);
 256
 257         return 0;
 258 }
 259
 260 static struct local_timer_ops twd_lt_ops __cpuinitdata = {
 261         .setup  = twd_timer_setup,
 262         .stop   = twd_timer_stop,
 263 };
 264
 265 static int __init twd_local_timer_common_register(void)
 266 {
 267         int err;
 268
 269         twd_evt = alloc_percpu(struct clock_event_device *);
 270         if (!twd_evt) {
 271                 err = -ENOMEM;
 272                 goto out_free;
 273         }
 274
 275         err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt);
 276         if (err) {
 277                 pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err);
 278                 goto out_free;
 279         }
 280
 281         err = local_timer_register(&twd_lt_ops);
 282         if (err)
 283                 goto out_irq;
 284
 285         return 0;
 286
 287 out_irq:
 288         free_percpu_irq(twd_ppi, twd_evt);
 289 out_free:
 290         iounmap(twd_base);
 291         twd_base = NULL;
 292         free_percpu(twd_evt);
 293
 294         return err;
 295 }
 296
 297 int __init twd_local_timer_register(struct twd_local_timer *tlt)
 298 {
 299         if (twd_base || twd_evt)
 300                 return -EBUSY;
 301
 302         twd_ppi = tlt->res[1].start;
 303
 304         twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0]));
 305         if (!twd_base)
 306                 return -ENOMEM;
 307
 308         return twd_local_timer_common_register();
 309 }
 310
 311 #ifdef CONFIG_OF
 312 const static struct of_device_id twd_of_match[] __initconst = {
 313         { .compatible = "arm,cortex-a9-twd-timer",      },
 314         { .compatible = "arm,cortex-a5-twd-timer",      },
 315         { .compatible = "arm,arm11mp-twd-timer",        },
 316         { },
 317 };
 318
 319 void __init twd_local_timer_of_register(void)
 320 {
 321         struct device_node *np;
 322         int err;
 323
 324         np = of_find_matching_node(NULL, twd_of_match);
 325         if (!np) {
 326                 err = -ENODEV;
 327                 goto out;
 328         }
 329
 330         twd_ppi = irq_of_parse_and_map(np, 0);
 331         if (!twd_ppi) {
 332                 err = -EINVAL;
 333                 goto out;
 334         }
 335
 336         twd_base = of_iomap(np, 0);
 337         if (!twd_base) {
 338                 err = -ENOMEM;
 339                 goto out;
 340         }
 341
 342         err = twd_local_timer_common_register();
 343
 344 out:
 345         WARN(err, "twd_local_timer_of_register failed (%d)\n", err);
 346 }
 347 #endif